Genetic Assessment of Striped Newt Populations

This project sought to determine the amount of gene flow and degree of genetic variation (genetic health) within and among striped newt populations throughout the range of the species (southern Georgia and northern Florida) using next generation sequencing techniques (ddRADSeq) to acquire single nucleotide polymorphisms (SNPs) for individual samples. Next generation sequencing is a relatively new technique that can be used to identify thousands of SNPs for population level comparisons, resulting in more power and finer resolution than earlier methods to detect population differences. 

Researchers genotyped 245 samples from 20 localities on 15 properties throughout the species’ range. However, after filtering SNPs, researchers describe a final dataset of 172 individuals from 15 localities on 11 properties characterized by 12,720 SNPs. Understanding the level of genetic diversity within populations from different regions and estimating the level of gene flow among populations provides information that is critical to understanding long-term population viability and can be used to make sound management and listing recommendations for this rare and declining species.

This study found three major results that could help resource managers:

1) Sample sites grouped into seven genetic clusters.
2) the SNP data are consistent with previous mtDNA data that suggests that Eastern versus Western sites are genetically differentiated. Moreover, researchers found an overall pattern of isolation-by-distance.
3) Pairwise comparisons of genetic diversity (i.e. heterozygosity) show that stronghold sites exhibit significantly higher genetic diversity than isolated sites. Overall, these data confirm that isolated sites that contain striped newts tend to exhibit little gene-flow between them and exhibit low levels of genetic diversity. In contrast, stronghold populations exhibit evidence of gene flow both within the stronghold and, in the case of Jennings State Forest and Ordway-Swisher Biological Station, between strongholds.